Learn to Program with Minecraft Plugins (2nd edition)

Learn to Program with Minecraft Plugins (2nd edition)

I have the German version of the book and everything worked fine on my Mac but then it came to CanaryMod. I started it first with start_minecraft and then with start_minecraft.mac . The server started and it showed as online in Minecraft. When I tried to join it it first said Logging in and then Minecraft crashed. So I did not get kicked but my Minecraft crashed. What can I do now?